Proportional solenoids are well known in the art and provide a force versus stroke curve that allows the output force of the solenoid to be proportional to the electrical current applied to the coil and that is independent of armature position over the working range of the stroke. This proportionality of the output force permits such a solenoid to either fully or partially operate a load by selectively applying either full or partial electrical current to the solenoid coil, thereby delivering a selective output force.
A typical solenoid includes a removable coil unit, an armature assembly, and an armature housing. The armature assembly includes an armature and a push pin that are reciprocally mounted within the armature housing. The armature housing includes a stator and a tube section in which the armature reciprocates. When electrical current is applied to the coil unit, the armature assembly moves longitudinally within the armature housing in response to a magnetic flux path established by the solenoid coil. The output force generated by the solenoid is dependent upon the amount of electrical current applied to the solenoid coil. A variety of concerns relate to the manufacture of solenoids. One concern relates to manufacturing a durable solenoid at a competitive price. Another concern relates to manufacturing a solenoid having a minimum number of parts. A further concern relates to minimizing run-out within a given solenoid. Still a further concern relates to manufacturing a solenoid that is easy to assemble and repair. An additional concern relates to providing a reliable solenoid at a reduced cost. A further concern relates to overcoming dilution and diffusion problems associated with heating an armature housing during the manufacturing process. Moreover, a further concern relates to providing a simplified solenoid manufacturing process that yields a solenoid capable of withstanding the extreme conditions presented by construction vehicles.